Cut pork belly into strips that are about 2 cm wide.
Pre-heat a wide, heavy-bottomed pot to medium to high heat so it’s ready for frying. You can use a frying pan, but the pot limits the amount of oil spray from frying the pork.
Salt each side of the pork belly and fry in 2 tbsp of olive oil until each side has browned. Do this in batches if you cannot fit all strips in the frying pan.
Place browned belly in an oven dish while you prepare the sauce. The dish should be big enough to accommodate all pork belly laying on its side.
Preheat oven to 160°C.
Using the same pot you used for frying, fry onions until they become translucent.
Add celery and peppers, add a dash of salt and give everything a good stir every few minutes to loosen the brown bits that became stuck to the bottom of the pan while frying the pork. This is all good flavour that you want in the sauce.
After 10 minutes add ginger and garlic and fry for a couple of minutes.
Add brown sugar, lemon juice and mustard powder. Cook for 2 more minutes.
Add tomato puree and stir in.
Add tinned tomato (crush tomatoes first if using plum tomatoes), then add chicken stock.
Once sauce comes to the boil it is ready to pour over the pork belly.
Cook at 160°C for 2.5 hours on the centre shelf of your oven.
Serve with rice or mash/roasted potatoes.